We were on our way soon after six; and, on leaving behind the bushes and small trees that grow on the skirts of the irrigated ground, we entered on a wide bare plain, stretching unbroken as far as the eye can reach, which forms the most singular feature in the aspect of this part of Marocco. The surface is covered with calcareous rough gravel, mixed in places with siliceous concretions. The scanty vegetation was already nearly all dried up, and it was not without difficulty that we secured specimens of most of the few species that can endure the parching heat and drought. Conspicuous among these was _Peganum Harmala_, forming at intervals green patches amid the general barrenness. _Stipa tortilis_ was frequent, but mostly dried up, and here and there occurred tufts of a meagre variety of _Avena barbata_. More interesting than these were a diminutive annual species of _Echium_ (_E. modestum_, Ball) and two species of _Centaurea_—one hitherto known as _Rhaponticum acaule_ of Decandolle, the other, before undescribed (_C. maroccana_, Ball). In its general aspect, and in the character of its vegetation, this region bears a striking likeness to the stony portions of the Sahara, and we were not sorry to include this among our Marocco experiences, though well pleased that the acquaintance was not to be much prolonged. Some six or seven miles east of Aïn Oumast we passed a short way north of Sidi Moktar, the tomb of a saint much venerated in this region, and the last spot where for a long distance water is to be found at all seasons. This is one of the halting-places, called _Nzelas_, frequented by ordinary travellers who follow this road. The _Nzela_ is one of the peculiar institutions of this country deserving of some notice. The Marocco Government recognises, at least in theory, the duty of protecting travellers from violence to their persons and goods; for without some provision for the purpose the small amount of trade now existing between the interior and the coast could scarcely continue to exist. As well as all other executive functions, the sovereign commits this to the Governor of each province, who accordingly stations a few armed men at the places where travellers are accustomed to halt. Such a post is a _Nzela_. It does not imply the existence of any shelter, and still less of any supplies for the sustenance of men and cattle. In a country where the sparse population lives in tents or temporary sheds, the traveller must provide such things for himself; but at a _Nzela_ the wayfarer may count on security from violence, and the guards are entitled to a trifling payment for each beast of burden that is committed to their protection. From any demands of this nature, as well as from the tolls that are levied on passing from one province to another, we were declared by our escort to be free, as personages travelling under the direct authority and protection of the Sultan. The boundaries of the three provinces of Shedma, Mtouga,